The present invention relates to a high volume self-cleaning filter which may be preferably used to filter fluids containing solid contaminants.
Fluid filtering systems are known in which two filter units are arranged in parallel such that when one unit is in service the other unit is out of service. This arrangement allows the latter unit to be cleaned or maintained while the system remains in service.
Cleaning of the out-of-service unit may be affected by back-flushing of the filter element, i.e., causing a flow of fluid through the filter in the direction opposite the normal filtering flow, by means of a rotary member having nozzles through which high pressure fluid is discharged. In this way foreign matter adhering to the surface of the filter element is washed off and out of the filter unit.
On completion of the back-flushing, the unit is then ready to be brought back into service. Thus, when the other unit becomes sufficiently contaminated, the newly cleaned unit may be brought back on line and the contaminated filter taken out of service for cleaning. Continuous filtration by the system can therefore proceed unhindered.
A problem in many such filtering systems, however, is with materials which tend to plasticize and blind the filter element. This problem is particularly evident in filtering operations involving fluids containing biological contaminants, such as fats and proteins. For example, in processing apparatus for carcasses, such as poultry carcasses, fluids such as coolant liquids (for storage and transportation) or heating liquids such as scalding water (to facilitate removal of feathers) are contaminated by fats from the carcass. Fats and similar biological contaminants have a tendency to agglomerate and form sheets which can quickly foul most filter systems. Accordingly, there is a particular need in the art for a filtering system which can provide continuous filtering of fluids containing solid contaminants.